That is something better done with Javascript. If you insist on doing it on the server, you'll need to inspect the setting of the User-Agent header. Note that this is not fool-proof. It si extremely easy to spoof this header.

Thank u Bear I got the code just now and its working. I required it bcos my Javascript( building multiline and combo box in it) doesnt work properly in mozilla. Can you get me some suggestion for making it work in Mozilla also?